Each year, 150,000 infants (1% - 3% of all U.S. births) are born with some form of physical or mental birth defect. As it is sometimes necessary to treat women with medications that cause birth defects, physicians must counsel women about medication risks and contraceptive options. In a recent analysis of the 1998-2000 National Ambulatory Medical Care Surveys, I found that generalist physicians provide ambulatory care to 45% of women using potentially teratogenic medications, but rarely (less than 20% of the time) provide contraceptive counseling. The reasons why many generalist physicians do not provide this counseling are not known. I seek a K23 award to strengthen my abilities to develop effective interventions to prevent birth defects resulting from inappropriate use of teratogenic medications by women of childbearing age. Specifically, I propose to conduct a retrospective cohort study of 650,000 women of reproductive age served by Northern California Kaiser Permanente pharmacies to identify which potentially teratogenic medications are most frequently prescribed without use of highly effective contraception (Aim 1);to conduct a cross sectional study of gaps in knowledge of primary care physicians that may contribute to unsafe prescription of teratogenic medications (Aim 2);and to evaluate the effect of a previously implemented clinic-based intervention to increase physician awareness of patients'contraceptive practices on unsafe prescription of teratogenic medications among approximately 190,000 women of childbearing age (Aim 3). To achieve these aims, I have assembled a mentoring committee whose expertise spans the relevant disciplines of epidemiology and general medicine (Drs. Grady and Gonazales) and gynecology (Dr. Darney). In addition, I have scientific advisors with expertise in reproductive epidemiology (Dr. Carmichael), reproductive social science (Dr. Joffe), patient safety (Dr. Wachter), survey instrument design (Dr. Stewart), biostatistics (Dr.Vittinghoff), risk assessment (Dr. Bindman), and use of the Kaiser Permanente databases (Dr. Shaber).Their mentorship, as well as a focused training and research plan facilitated by a K23 award, will enable me to achieve my goal of developing an independent career in patient-oriented clinical research, focused on facilitating contraceptive service provision to limit adverse birth outcomes, while furthering the NICHD's mission of ensuring that every person is born healthy and wanted.